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Abstract:

Embodiments of the present invention are directed to adjustable test
probe tips that are indexable. In one embodiment a mechanism is coupled
to a probe tip so that the mechanism may be used to index the probe tip
to a plurality of particular positions. A label portion may be provided
to communicate to a user that the length of the exposed probe tip is less
than a particular length, such as the maximum length an exposed probe tip
may be for a particular application.

Claims:

1. A test probe, comprising: (a) a conductive member having an
electrically conductive tip and further having a first end of the
conductive member opposite of the tip; (b) an insulative member
surrounding a first portion of the conductive member and the first end of
the conductive member so that a second portion of the conductive member
is exposed from the insulative member, the conductive member being
operable to move relative to the insulative member; and (c) a locking
mechanism that is rotatable relative to the conductive member in a first
direction to prevent the conductive member from moving relative to the
insulative member and rotatable relative to the conductive member in a
second direction to allow the conductive member to move relative to the
insulative member.

2. The test probe of claim 1, further comprising a label portion that
corresponds to the length of the conductive member exposed from the
insulative member, the label portion provided through an opening in the
insulative member.

3. The test probe of claim 2, wherein the label portion corresponds to
the length of the conductive member being exposed from the insulative
member by indicating a category rating for the exposed length.

4. The test probe of claim 1, wherein the locking mechanism is positioned
at a first end of the insulative member so that the locking mechanism
provides pressure to the first portion of the conductive member.

5. The test probe of claim 1, wherein the locking mechanism is positioned
near the first end of the conductive member.

6. The test probe of claim 1, wherein the locking mechanism is rotatable
relative to the insulative member.

7. The test probe of claim 1, wherein the locking mechanism is a cap that
is threaded onto an end of the insulative member.

8. A method for adjusting a length of a conductive member having a probe
tip exposed from a first end of an insulative material, comprising: (a)
rotating a locking mechanism relative to the conductive member into a
first position to allow the conductive member to move relative to the
insulative member; (b) moving the conductive member to expose a first
length of the probe tip from the first end of the insulative material;
and (c) rotating the locking mechanism relative to the conductive member
into a second position to prevent the conductive member from moving
relative to the insulative member.

9. The method of claim 8, further comprising indicating that the first
length of the probe tip exposed from the first end of the insulative
material is equal to or less than a particular length.

10. The method of claim 8, further comprising indicating that the first
length of the probe tip exposed from the first end of the insulative
material meets a requirement for a particular application.

11. The method of claim 8, further comprising: (a) rotating a locking
mechanism relative to the conductive member into the first position to
allow the conductive member to move relative to the insulative member;
(b) moving the conductive member to expose a second length of the probe
tip from the first end of the insulative material; and (c) rotating the
locking mechanism relative to the conductive member into the second
position to prevent the conductive member from moving relative to the
insulative member.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of U.S. patent application Ser.
No. 12/333,096, filed Dec. 11, 2008, the disclosure of which is hereby
expressly incorporated by reference herein.

TECHNICAL FIELD

[0002] This invention relates generally to test instrument lead probes,
and more specifically one or more embodiments relate to adjustable test
probe tips.

BACKGROUND

[0003] Test instruments, such as multimeters, voltage meters,
oscilloscopes and the like, are used to measure electrical parameters in
various electrical devices. FIG. 1 illustrates an exemplary test
instrument 100. The test instrument 100 has a test probe 102 that is
coupled to an input/output 104 of the test instrument 100. The test probe
102 has a test lead 106 having a first end 108 that is coupled to the
input/output 104 of the test instrument 100 and a second end 110 that is
coupled to a probe body 112. The probe body 112 includes a tip 114, which
is coupled to a test point (not shown) of a device (not shown) to be
measured or tested. As will be clear to a person having ordinary skill in
the art, a second test probe (not shown), such as a ground connector, may
be coupled to input/output 105.

[0004] In general, different length test probe tips are used in various
test applications. In the past, to accommodate the need for different
length probe tips, various test probe assemblies having different probe
tip lengths were used with test instruments. For instance, a user may
have two sets of test probes, one probe set with long length probe tips
and another set with short probe tips. Another method for accommodating
for the need of different length probes has been to use probe tips that
are removable from the probe holder or body. Thus, rather than replacing
the entire probe assembly, only the probe tip needs to be replaced.
However, both of these solutions require a user to have to manage two
sets of test probes, either the entire test probe assembly or test probe
tips. Often test points are located in an obstructed location and having
multiple test probes or probe tips can result in problems for the user
when switching out the different probes. For instance, the user may have
difficulty carrying the extra probes or the equipment may put the user in
an awkward position so that it is a challenge to change out the probes.
Additionally, by having separate test probes, the user may misplace,
drop, or lose the probes so that the appropriate probe or probe tip is
not available when needed.

[0005] More recently, however, test probes have been designed with probe
tips that are slideable within the probe holder or body. Thus, rather
than replacing the entire probe assembly when a different length probe
tip is required, the probe tip slides in and out of the probe body and is
locked into position at a desired length. For instance, when a longer
probe tip is required, a locking mechanism that holds the probe tip
within the probe body may be released so that the probe tip is free to
move within the probe body. A user may then slide the probe tip so that a
greater portion of the probe tip is exposed from the probe body and lock
the probe tip into position. Therefore, rather than replacing the probe
assembly or the probe tip, a single probe tip may act as a varying length
probe tip. When a long probe length is needed, the probe tip slides out
of the probe body so that more of the probe tip extends from the probe
body. When a short probe length is needed, some of the exposed probe tip
slides back into the probe body so that less of the probe tip extends
from the probe body. Consequently, a single probe tip provides
versatility and a user does not need to carry around probes having
varying lengths.

[0006] Recently, safety standards have been developed that limit the
length of the exposed probe tip. In particular, the International
Electrotechnical Commission (IEC), under the guidance of Technical
Committee (TC66), generated a safety standard for Test and Measurement
Equipment related to test probes referenced as IEC-61010-031. This
standard specifies requirements for test probe tips for various test
applications. For instance, the safety standard specifies the length of
the exposed metal tip of the probe used in industrial applications,
referred to as category III (CAT III) and category IV (CAT IV),
installation must be less than 4 mm in length. The probe tip for low
energy applications, such as used in household applications or category
II (CAT II) installations, must be less than 18 mm in length. Having a
probe tip with exposed metal 18 mm in length is important because this
allows users to easily insert the probe tip into a standard wall socket
for quick and accurate measurement, which is not possible with a 4 mm
probe tip. For industrial applications (CAT III and CAT IV) where high
energy exists, a reduced probe tip of 4 mm is important to help reduce
risk of arcs and arc flash hazards, which is not an issue in CAT II
environments.

[0007] Therefore, when using a slideable probe tip describe above, a user
will not know whether the exposed length of the probe tip is within the
specified length to meet the safety standard unless a measurement is made
on the exposed length of the probe tip each time the probe tip length is
adjusted. This requires a user to carry a measurement tool and results in
a time consuming second step. Although a user may expose a portion of the
probe tip that is significantly less than required by the safety
standards discussed above and not have to make a measurement, most
applications require the entire amount allowed under the safety standard.
For instance, in household application, a user will need a probe tip to
be very close to the 18 mm maximum length because it will allow the user
to insert the probe tip into standard wall sockets.

[0008] There is, therefore, a need for a test probe having an adjustable
length probe tip that indexes to predetermined lengths. Additionally,
there is a need for an adjustable probe tip that communicates to a user
the length of the exposed probe tip.

SUMMARY

[0009] The present invention is directed toward an apparatus and method
for indexable adjusting test probe tips. In one aspect of the invention,
a test probe includes a conductive member having a first end and a second
end. An electrically conductive tip defines the second end, and an
insulative member surrounds at least the first end of the conductive
member so that a particular first length of the conductive member is
exposed from the insulative member. A slide member is coupled to the
conductive member to index the conductive member relative to the
insulative member so that a particular second length of the conductive
member is exposed from the insulative member.

[0010] In another aspect of the invention, a test probe includes an
insulative member having an opening along its length and a conductive
member having a first end and a second end, where an electrically
conductive tip defines the second end. The first end of the conductive
member is positioned in the opening in the insulative member. A slide
member is coupled to the conductive member and is operable to move the
conductive member from a first length being exposed from the opening of
the insulative member to a second length of the conductive member being
exposed from the opening of the insulative member, the second length
being a specific distance from the first length.

[0011] In another aspect of the invention, a test probe includes a
conductive member having a length with a first end and a second end,
where an electrically conductive tip defines the second end of the
conductive member. The test probe further includes an insulative member
surrounding a first portion of the length of the conductive member and
the first end of the conductive member so that a second portion of the
length of the conductive member is exposed from the insulative member,
where the conductive member is operable to move relative to the
insulative member. The test probe further includes a locking mechanism
that when locked, prevents the conductive member from moving relative to
the insulative member. The test probe may include a label portion that
corresponds to the length of the conductive member exposed from the
insulative member.

DESCRIPTION OF THE DRAWINGS

[0012] The foregoing aspects and many of the attendant advantages of the
present disclosure will become more readily appreciated by reference to
the following detailed description, when taken in conjunction with the
accompanying drawings, wherein:

[0013]FIG. 1 is a schematic drawing of a test instrument in accordance
with prior art;

[0014] FIG. 2A is a top and a side view of a schematic drawing of a test
probe according to one embodiment of the invention;

[0015]FIG. 2B is a top view and a side view of a schematic drawing of a
test probe according to one embodiment of the invention;

[0016] FIG. 2C is a schematic drawing of the slide button according to one
embodiment of the invention;

[0017]FIG. 3A is a top view of a schematic drawing of a test probe
according to one embodiment of the invention;

[0018]FIG. 3B is a bottom view of a schematic drawing of the test probe
in FIG. 3A.

[0019]FIG. 3c is a cross sectional schematic drawing of the test probe in
FIG. 3A;

[0020] FIG. 4A is a schematic drawing of a test probe according to one
embodiment of the invention;

[0021] FIG. 4B is a schematic drawing of a test probe according to one
embodiment of the invention;

[0022] FIG. 5A is a schematic drawing of a test probe according to one
embodiment of the invention; and

[0023]FIG. 5B is a schematic drawing of a test probe according to one
embodiment of the invention

DETAILED DESCRIPTION

[0024] Embodiments of the present invention are directed toward test
probes used with test and measurement equipment, and more particularly,
one or more embodiments relate to adjustable test probe tips that are
indexable. In some embodiments, a probe tip is indexed using a mechanical
system, an optical system, or a combination of thereof. Certain details
are set forth below to provide a sufficient understanding of the
embodiments of the invention. However, it will be clear to one skilled in
the art that various embodiments of the invention may be practiced
without these particular details.

[0025] FIGS. 2A and 2B illustrates a respective top view and a side view
of a test probe 200 according to one embodiment of the invention. The
test probe 200 includes a probe body 202, a test lead 204, and a probe
tip 206. The probe body 202 is made from an insulative material. The
probe tip 206 is made from an electrically conductive material, and is
configured to be placed in electrical communication with a test point
(not shown) of a test device (not shown). As discussed above, the test
lead 204 is configured to be coupled to the input/output of a test
instrument (not shown).

[0026] The probe tip 206 is moveable within the probe body 202.
Additionally, the probe tip 206 is indexable. That is, the probe tip 206
may be indexed to a plurality of positions where each position defines
the length of the exposed probe tip 206. In the embodiment shown in FIG.
2A and 2B, the probe tip 206 is indexed to two positions. A first
position 220 is shown in FIG. 2A and a second position 222 is shown in
FIG. 2B. A slide button 210 is provided within the probe body 202 for
moving and indexing the probe tip 206. The slide button 210 is coupled to
the probe tip 206 within the probe body 202 so that when a user moves the
slide button 210 the probe tip 206 also moves. For instance, in one
embodiment, as the slide button 210 is moved towards the probe tip 206,
the length of the probe tip 206 exposed from the probe body 202
increases.

[0027] FIG. 2C shows one embodiment of the slide button 210 disclosed in
FIGS. 2A and 2B. The slide button 210 includes a first label portion 214,
a second label portion 216, and a lever portion 218. The first and second
label portions 214 and 216 communicate to the user the length of the
exposed part of the probe tip 206. In the embodiment shown, the first and
second label portions 214 and 216 are a visual element that describes the
category installation rating to indicate that the length of the exposed
part of the probe tip 206 is less than the specified length for that
particular category. FIGS. 2A and 2B show some of the detailed features
of the slide button 210 discussed above. For instance, in FIG. 2A the
first label portion 214 is positioned in the opening 212 to communicate
that the probe tip 206 is indexed so that the length of the exposed probe
tip 206 is less than the required length for a category III rating.
Additionally, in FIG. 2B the second label portion 216 is positioned in
the opening 212 to communicate that the probe tip 206 is indexed so that
the length of the exposed probe tip 206 is less than the required length
for a category II rating. As can be seen in FIG. 2B, when the second
label portion 216 is positioned in the opening 212, the first label
portion 214 is not positioned in the opening 212. As will be clear to a
person having ordinary skill in the art, the first and second label
portions 214 and 216 may provide any type of communication to a user,
such as physical markings that can be detected by touch or visual
markings, which communicates the length of the probe tip 206 that is
exposed from the probe body 202.

[0028] As discussed above, in the embodiment shown in FIG. 2A the probe
tip 206 is indexed in a first position 220. In particular, the lever
portion 218 of the slide button 210 is positioned adjacent a side of the
probe body 202 that is coupled to the lead wire 204. The probe body 202
includes an opening 212 in the probe body 202 to expose the first and
second label portions 214 and 216 of the slide button 210 to a user. For
instance, while the probe tip 206 is indexed in the first position 220,
the first label portion 214 of the slide button 210 is exposed to a first
side of the opening 212 so that a user may determine from the first label
portion 214 the length of the exposed part of the probe tip 206 or the
category rating for which the probe tip 206 may be used. When the lever
portion 218 of the slide button 210 is moved to a second position shown
in FIG. 2B, the exposed part of the probe tip 206 is indexed to a second
position 222. The second label portion 216 of the slide button 210 is
exposed to a second side of the opening 212. Therefore, the second label
portion 216 correlates to the indexed second position 222 of the probe
tip 206 and the first label portion 214 correlates to the indexed first
position 220.

[0029] In the embodiment shown in FIG. 2A and 2B, the test probe 200
includes a finger guard 208 to prevent a user's hand from slipping into
the exposed probe tip 206 when the probe tip 206 is being used. However,
as will be clear to a person having ordinary skill in the art, the finger
guard 208 may not be used in some embodiments.

[0030] FIGS. 3A-3C illustrate various views of a test probe 300 having an
indexable probe tip 206 according to another embodiment of the invention.
FIG. 3A is a top view of the test probe 300, FIG. 3B is a bottom view of
the test probe 300, and FIG. 3c is a cross sectional view of the test
probe 300 along the line A-A in FIG. 3A. Most of the components of the
test probe 200 in FIGS. 2A-2B are used in the test probe 300 in FIGS.
3A-3C. Therefore, in the interest of brevity, an explanation of their
structure and function will not be repeated. The test probe 300 differs
from the test probe 200 by the mechanism used to index the test probe tip
206. The test probe tip 206 is indexed by moving slide lever 230 along an
opening 231 in the probe body 202. The probe body 202 opening 231
includes a main channel 232 and two slots 234 and 236. The main channel
232 may be provided along a portion of the length of the probe body 202.
As a user moves the slide lever 230 along the main channel 232, the probe
tip 206 moves relative to the probe body 202. The slider lever 230 may be
rotationally biased towards slots 234 and 236 in the opening 231 of the
probe body 202. Alternatively, a user may slide the slide lever 230 into
the slots 234 and 236. In some embodiments, the slider lever 230 is
locked into each slot 234 and 236. Therefore, the slide lever 230 in
combination with the opening 231 in the probe body 202, provides
mechanical indexing of the probe tip 206.

[0031]FIG. 3B illustrates a bottom view of the test probe 300. The bottom
of the test probe 300 includes an opening 240 that exposes a first label
portion 242 to the user that provides an optical element to confirm the
indexed position of the probe tip 206. When the probe tip 206 is indexed
to a second position by moving the slide lever 230 into the slot 234, the
second label portion 244 is exposed through the opening 240 in the probe
body 202. In another embodiment, a label (not shown) is provided in 236
when the slide lever is positioned in slot 236. For instance, the slot
234 would indicate the length of the exposed probe tip 202 when the
slider lever 230 is positioned in the slot 236. Conversely, the slot 236
would indicate the length of the exposed probe tip 206 when the slide
lever 230 is located in the slot 234.

[0032]FIG. 3c shows the slide lever 230 positioned in slot 236 of opening
231. When the slide lever 230 is positioned in the slot 236, the exposed
length of the probe tip 206 from the probe body 202 is the length shown
in FIGS. 3A-3C. However, if the slide lever 230 were positioned into slot
234, the length of the probe tip 206 exposed from the probe body 202
would be less than the length shown in FIGS. 3A-3C. When the slide lever
230 is positioned into slot 234, the second label portion is exposed
through the opening 240 in the probe body 202.

[0033] FIGS. 4A and 4B illustrate a test probe 400 having an indexable
probe tip 206 according to another embodiment of the invention. Most of
the components of the test probe 200 in FIGS. 2A-2B are used in the test
probe 400 in FIGS. 4A-4B. Therefore, in the interest of brevity, an
explanation of their structure and function will not be repeated. FIG. 4A
shows the test probe tip 206 indexed in a first position 220, and FIG. 4B
shows the test probe tip 206 indexed to a second position 222. The probe
tip 206 is moved by manually sliding the probe tip 206 within the probe
body 202. In this embodiment, the probe tip 206 is indexed optically via
a label 242 positioned in an opening or window 240 provided in the probe
body 202. For instance, in FIG. 4A the probe tip is indexed to a first
position 220 when a first label portion indicating a category III is
located in the opening 240 of the probe body 202. The length of the probe
tip 206 extending from the probe body 202 is, therefore, within the limit
defined by a category III rating. In FIG. 4B, however, the probe tip 206
is indexed to a second position 222, a category II rating, as indicated
by a second label portion positioned at the opening 240 in the probe body
202. Therefore, the length of the probe tip 206 extending from the probe
body 202 is within the limits defined by the category II rating.

[0034] As stated above, the probe tip 206 slides into and out of the probe
body 202. A front locking cap 250 is provided to lock the probe tip 206
into position after the probe tip 206 has been indexed to its desired
location. In the embodiment provided in FIGS. 4A-4B, the front locking
cap 250 is locked or unlocked by rotating the front locking cap 250
relative to the probe body 202. In this embodiment, the front locking cap
250 has threads that mate with threads on the probe body 202. However, as
will be clear to a person having ordinary skill in the art, the front
locking cap 250 may use any means for locking the probe tip 206 into
position. Once a user has optically determined that the probe tip 206 has
been properly indexed, such as by centering the category rating in the
opening of the probe body 202, the user may rotate the front locking cap
250 to lock the probe tip 206 into position.

[0035] FIGS. 5A-5B illustrate a test probe 500 having an indexable probe
tip according to another embodiment of the invention. FIG. 5A shows the
test probe tip 206 indexed in a first position 220, and FIG. 5B shows the
test probe tip 206 indexed to a second position 222. Most of the
components of the test probe 400 in FIGS. 4A-4B are used in the test
probe 500 in FIGS. 5A-5B. Therefore, in the interest of brevity, an
explanation of their structure and function will not be repeated. The
test probes in FIGS. 5A-5B differ from the test probes in FIGS. 4A-4B by
having a back locking cap 252 in test probe 500, rather than a front
locking cap 250 in test probe 400. The back locking cap 252 provides a
similar function as the front locking cap 250 in that it is operable to
lock the probe tip 206 into a position. In particular, after the probe
tip 206 is indexed to a particular position, the back locking cap 252 may
be rotated or snapped into position to lock the probe tip 206 into the
indexed position. As in the test probe 400 shown in FIGS. 4A-4B, the test
probe 500 in FIGS. 5A-5B is indexed optically via an opening 240 in the
probe body 202.

[0036] Although the present invention has been described with reference to
the disclosed embodiments, persons skilled in the art will recognize that
changes may be made in form and detail without departing from the spirit
and scope of the invention. For instance, the test probe tip may be
indexable to a plurality of positions. Additionally, the probe tip may be
fully retractable within the probe body. The test probe tip may be
indexed optically, mechanically, or a combination thereof. Additionally,
any means of communication may be used to communicate to a user the that
the probe tip the position in which the probe tip has been indexed, such
as visual element, audio element, or a raised surface on a label portion
that a user can feel to determine the length of the exposed probe tip or
the category rating. Additionally, any method of locking the probe tip
into position may be used. Such modifications are well within the skill
of those ordinarily skilled in the art. Accordingly, the invention is not
limited except as by the appended claims.